Tinfoil was my own mod. Initially I saw the mod but it was with waxed cardboard and I decided to use tinfoil. It worked great for noise reduction without and effect on function of skimmer.
However I never contemplated chemical reaction of tinfoil (I only used skimmer for a cpl months and upgraded, but saw no death in that time) and if that is an issue I would supplement with another malliable substance that wont deteriorate in the water or effect spray injection